442 PROF. F. W. DYSON: DETERMINATIONS OF WAVE-LENGTH FROM SPECTRA 
Chromium. 
Chromium is very strong in the chromospheric spectrum. The only strong spark 
line in Exner and Haschek’s list which is missing is 3976‘82 of intensity 9. Strong 
arc lines are shown, but it is the enhanced lines which are strongest. In the 
following table the intensities in the sun, spark, and arc, are taken from Mr. Jewell s 
paper:— 
Enhanced lines 
Strong arc lines. 
Wave¬ 
length. 
Chromo¬ 
sphere. 
Sun. 
Spark. 
Arc. 
Wave¬ 
length. 
Chromo¬ 
sphere. 
Sun. 
Spark. 
Arc. 
3408 
4 
3 
20 
3 
3578 
1 
10 
20 
30 
3421 
4 
4 
10 
3 
3593 
2 
9 
10 
30 
3422 
4 
4 
10 
4 
3605 
1 
7 
20 
20 
3433 
5 
3 
10 
3 
4254 
3 
8 
50 
50 
3603 
2 
3 
10 
0 
4274 
3 
7 
30 
50 
Manganese, 
Manganese is not so strong as chromium, and only some of the strongest spark 
lines of Exner and Haschek’s list are shown. Some strong arc lines from 4754 to 
4823 are feebly shown, the strongest arc lines near 4030 are well shown. The 
strongest chromospheric lines are given below. 
Enhanced lines. 
Strongest arc lines. 
Wave¬ 
length. 
Chromo¬ 
sphere. 
Sun. 
Spark. 
Arc. 
Wave¬ 
length. 
Chromo¬ 
sphere. 
Sun. 
Spark. 
Arc. 
3442 
4 
6 
40 
7 
4030 
2 
12 
20 
30 
3460 
3 
4 
40 
3 
4033 
1 
10 
20 
25 
3474 
2 
4 
40 
— 
4034 
1 
8 
10 
20 
3483 
9 
5 
30 
3 
3488 
2 
4 
30 
3 
Iron. 
The following table gives some of the stronger iron lines from 3735 to 3930. Lines 
are avoided whose origin either in the sun or chromosphere is ambiguous. The 
intensities of the arc lines are taken from Kayser and IIunge’s list:— 
